1. Field of the Invention
This invention generally relates to asphalt-rubber compositions and systems and methods for preparing same.
2. Description of the Related Art
Asphalt pavement suffers from oxidative hardening over time. This oxidative hardening causes cracking of the pavement, potholes, and loose gravel on the surface. The addition of rubber, such as crumb rubber from recycled automobile tires, to an asphalt binder, substantially reduces the rate of oxidative hardening of asphalt pavement and increases the useful life of a road. This asphalt-rubber mixture is typically referred to as asphalt-rubber binder (ARB).
ARB and aggregates are typically mixed together and spread onto road surfaces to form asphalt pavement. Because prior art ARB is highly temperature sensitive, it can be applied to roads only under certain surface temperature and weather conditions. This in turn limits road paving activities to only a few months of the year in most regions of the country. Additionally, special heating/blending equipment are often required at job sites to keep the mixture free flowing and homogeneous. In some cases, additives are added to asphalt-rubber hot mix material to reduce segregation, crusting, or lumping of the crumb rubber. These additives, however, could have detrimental effects on other properties of the mixture. Thus, there is a current need for an improved ARB system that is less sensitive to environmental conditions and can be easily applied to surfaces without requiring expensive or complex equipment or additives to keep the mixture free flowing and homogeneous.